\begin{tikzpicture}
    \tkzDefPoints{0/0/O}
    \tkzDefPoint(90:1.5){M}
    \tkzDefPoint(270:1.5){N}
    \tkzDefPoint(160:1.5){A}
    \tkzDefPoint(20:1.5){B}
    \tkzDefPoint(130:1.5){C}
    \tkzDefPoint(50:1.5){D}

    \tkzDrawCircle[thick](O,A)
    \tkzDrawSegments(M,N  A,B  C,D)
    \tkzDrawPoint(O)
    \tkzLabelPoints[left](A,C)
    \tkzLabelPoints[right](B,D,O)
    \tkzLabelPoints[above](M)
    \tkzLabelPoints[below](N)
\end{tikzpicture}

